1. Field
The present invention relates to a control device of a synchronous rectifier and a power supply.
2. Description of Related Art
In recent years, various types of electronic devices such as a computer, a display device, various control devices or the like have been used to be matched with various requirements of the user at various spaces such as a house, an office, an industrial plant or the like.
In order to perform various operations to suitably address various requirements of the user, such electronic devices necessarily employ a power supply to supply the driving power required for operation thereof. The power supply may be employed within the electronic devices themselves, or may be established external thereto.
The power supply may employ a switching mode power supply (SMPS) method due to the advantages of the conventional power conversion efficiency and miniaturization benefits, amongst others.
The above-described SMPS type power supply can switch the power inputted to the primary side; transmit the switched power to the secondary side through a transformer; and output the direct current appropriate for use by rectifying the power transmitted from the secondary side.
On the other hand, in the case of the above-described power supply, the synchronous rectification type power supply can be employed to minimize the conduction loss by using the switching type synchronous rectifier SR synchronized with the primary side switching at the secondary side rectification terminal.
In case of such power supply of the synchronous rectifier variety, although the synchronous rectifier is switched on by being synchronized with the primary side switching off and the synchronous rectifier is switched off by being synchronized with the primary side switching on, in alternating relation, but, according to delaying the switching of the synchronous rectifier, an overlap phenomenon may be generated while the synchronous rectifier is switched on during the primary switching on, in this result, the output power becomes unstable and may destroy the insulation of the synchronous rectifier or the other devices.
In order to prevent such overlap phenomenon, although the dead time control technology or the like can be used, due to various reasons (for example, the switching frequency variation at the primary side), the dead time (the time interval between the off time of the synchronous rectifier and the switching on time at the primary side) may be varied; and, accordingly, it cannot be fixed and controlled with the optimum dead time in stabilizing the power system and the efficiency thereof.